Application Value Of The Dual-source CT Technology In Cervical Lymph Nodes

Objectives:1. To make a further discussion about the application value of VNCT technology upon the diseased cervical lymph nodes.2. In comparison with traditional FBP reconstruction, to make a discussion about the value of how the dual energy scan patterns combining SAFIRE can improve the diseased cervical lymph nodes image quality.3. To make a discussion about the diseased cervical lymph nodes display differences of each of dual energy deprived sequence, and evaluate its diagnostic value to the different types of diseased cervical lymph nodes.Materials and methods:Retrospectively analyze126patient CT materials in the distinct50cases, with lymph nodes diseases pathologically proven, where all the patients have been given the TNC as well as artery and substantial dual phases and energy scanning, so we get Sn140kV、80kV and the weighting linear fusion images. We get the VNC images and iodine images by using the " Liver VNC " software, the nonlinear fusion images by using "Optimal Contrast" and the60-180kev single-energy spectrum images by using "Mono Energetic" software. Make a comparative study on the average CT value of the diseased cervical lymph nodes VNC images and CNC images, SNR、CNR and subjective image quality; Make a comparative study on the radiation dose between the TNC and dual energy scan (shown as CTDIvol and DLP). We can get images of set A (Sn140kVp, FBP), set B (80kVp,FBP), set C (FBP) by routine reconstructing,Sn140kVp、80kVp and the linear fusion images on the substance phase under dual energy scanning patterns, and then get images of set D (Sn140kVp,SAFIRE), set E(80KVp,SAFIRE) and set F (the linear fusion images, SAFIRE) by SAFIREing Sn140kVp、80kVp and the linear fusion images. Measure the6images about their parenchymal tissues of lymphadenopathy, single-level sternocleidomastoid, single-level jugular vein and the average CT value and image noise. Then calculate and compare the SNR and CNR of parenchymal tissues of lymphadenopathy between any two sets of the images; and subjectively evaluate the6images quality. Make a comparison among each of derived sequences (iodine images, the linear fusion images, the nonlinear fusion images and70kev single-energy spectrum images) of their different display of lymph nodes diseases, make a discussion upon the value of iodine images and energy spectrum decay curve of distinguishing different types of pathology.Results:1. Pathology result:Among the total126lymph nodes, there are37benign lymphadenopathy lesion into lymphonodus tuberculosis and non-specific lymphangitis (29.3%), where there are8lymphonodus tuberculosis (6.3%) and non-specific lymphangitis (23.0%);44malignant lymphangitis lesion into thyroid gland metastatic lymph nodes and other cancer metastatic lymph nodes (34.9%), among which there are29thyroid gland metastatic lymph nodes (23.0%),15other cancer metastatic lymph nodes (11.9%);45lymphomas (35.7%).2. Make a comparison of the diseased lymph node between its TNC and the average CT value, SNR value and CNR value, respectively, of the dual phase VNC, the results are as followed:TNC has no difference (65.54±5.14、69.43±11.95,68.78±10.1, F=1.372, P=0.183) with the average CT value of VNC (A) and VNC (V), but it has statistical difference with SNR (6.71±2.84、10.99±4.08、10.93±5.17,F=18.417, P=0.000and CNR(1.42±0.74、3.13±0.94、3.94±1.56,F=8.302, P=0.000) of the dual phase VNC, where SNR and CNR are both higher than TNC. There are no statistical difference between SNR (t=0.053, P=0.955) and CNR (t=1.237, P=0.219)3. TNC images and the dual phase VNC produced by the second generation DSCT can show both the necrosis and large calcification of diseased lymph node, where there are no statistical difference. But VNC is weak at displaying slight calcification.4. The differences by comparing the subject image quality of CNC, arterial phase VNC and substantial phase have no statistical significance (H=3.042, P>0.05)..5. In comparison with the conventional III scan, the reduction of radiation effective dose of the second generation of DSCT dual energy and phases scan is (10.99-18.20)=2.79mSv, about25%.6. All of the differences among the average CT value and SD of parenchymal tissues of lymphadenopathy, single-level sternocleidomastoid, single-level jugular vein of the6images, which are produced by conventional FBP reconstructing and SAFIRE, have the statistical significance (P<0.05), where the minimum of the average CT value are all set D (140kVp,SAFIRE), with results as:(75.09±15.58,56.96±6.89,173.17±14.95), while the maximum are all set E (80kVp, SAFIRE) with results as (117.90±28.23、75.35±6.82、263.34±25.86); the maximum of SD value are all set B (80kVp,FB), with results as (9.75±1.39,8.85±1.18,11.80±0.21), while the minimum are all set F (linear fusion, SAFIRE), with results as (3.62±0.83,3.25±0.730,3.62±0.75). The SNR differences of parenchymal tissues of lymphadenopathy of6images have the statistical significance (P<0.01), where the maximum SNR of the parenchymal tissues of lymphadenopathy are set F (26.72±10.19) and the minimum are set B (11.50±4.11). Make a further comparison among any two of the6images, and get the results:there are statistical significance(P<0.01) between below images:between set A and set E (Sn140kVp, FBP), set F; between set B and set E, between set F and set C (linear fusion, FBP), set D. There are no statistical significance (P>0.05) between any two of the rest images. The CNR differences of parenchymal tissues of lymphadenopathy of6images have the statistical significance (P<0.01), where the maximum CNR of the parenchymal tissues of lymphadenopathy are set F and the minimum are set D. Make a further comparison among any two of the6images, and get the results:there are statistical significance(P<0.05) between below images:between set D and set C, set E, set F; between set B and set E, set F, between set A and set F. There are no statistical significance (P>0.05) between any two of the rest images. The subjective quality grading of the6images is based on Kruskal-wallis verification with multi-samples, and by means of statistics analysis, the differences have statistical significance (Chis-Square=60.28, P<0.01), with the results as:the maximum score is set E (4.78±0.46) and the minimum is set A (3.68±0.53). Score obtained by each of the image set is higher than3.7. Each of the dual energy derived sequence to the diseased lymph nodes shows:the differences between the relative enhancement value (REV) of the normal and diseased lymph node tissue substance and the CT value of iodine images have no statistical significance (P>0.05), where iodine images gets the iodine value of diseased lymph node tissue and can get the relative enhancement value of tissue substance much more directly. There are no statistical differences (P<0.05) between the REV of single-level sternocleidomastoid and iodine value. The differences of the CT value of diseased lymph node tissues substance of4groups of derived sequences, the ratio of diseased lymph node tissues substance to the normal lymph node tissues substance enhanced as well as the CNR between the normal lymph node tissues substance and the diseased lymph node tissues substance, is shown by means of single factor variance analysis and get the results diseased lymph node substance has the statistical significance (P<0.05), where the maximum difference between CT value is nonlinear fusion, with the rest followed by iodine images, single-energy spectrum image (70kev) and the linear fusion. There are statistical significance(P<0.05) of the ratio of the diseased lymph nodes to single-level sternocleidomastoid strengthening among different image sets, with the maximum as iodine images, followed by nonlinear fusion, single-energy spectrum image (70kev) and the linear fusion; the CNR from single-level sternocleidomastoid to the diseased lymph nodes among has no statistical significance (P>0.05).8. Iodine images:There is no significant difference between the average CT value between the benign and malignant diseased lymph nodes on arterial phase (P>0.05). There are differences (F=12.277, P<0.001) of the average CT value at iodine images between the different pathology types of diseased lymph node tissues on arterial phase, but there are no differences (F=1.278, P>0.05) on the substantial phase. The further comparison of the average CT value of any two dual phase iodine images among different pathology types of the diseased lymph nodes shows that there are differences (P<0.05) between lymph nodes with thyroid metastatic cancer, non-specific lymphangitis, tuberculous lymphadenitis, other lymph nodes with metastatic cancer and lymphoma; and no differences (P>0.05) between the rest. There are differences (P<0.05) of the average CT value of the enhanced dual phase iodine images based on the same pathology between lymph nodes with thyroid metastatic cancer and other lymph nodes with metastatic cancer; and no such differences (P>0.05) among lymphoma, tuberculous lymphadenitis and non-specific lymphangitis.9. Energy spectrum decay curve:in the scope of60-180keV, as the single energy keV value rises, the CT value, corresponding to5different tissues, decreases gradually, and the higher keV value is, the smaller the decreased range of the CT value is. In the scope of60-180keV, the5tissues are all shown as decay curve, having different slopes and decaying differently. There are statistical significance of overall differences (F=0.388, P>0.05) among the5tissues. The further comparison among the5tissues of their slope shows that the slope of lymph nodes with thyroid metastatic cancer is statistically different (P<0.05) from the slope of lymph nodes with other metastatic cancer, tuberculous lymphadenitis, non-specific lymphangitis and lymphoma; and the slope of lymphoma is statistically different (P<0.05) from lymph nodes with other metastatic and cancer tuberculous lymphadenitis; and no such differences (P>0.05) between the rest slopes. There are no statistical significance of slope differences between the5tissues on both arterial phase and substance phase in the enhanced dual phase scan.Conclusion:1. In the CT check of the diseased cervical lymph node, a dual energy enhanced scan can obtain both T dual phase enhanced images and VNC images, and there are no difference of the average CT value between TNC images and VNC images, their subjective image quality has no difference, too. Though there are difference between their SD, SNR and CNR, it does not affect the disease diagnose. Therefore, VNCT might replace CNT. 2. Dual energy substantial scan combining SAFIRE technology can both high SNR and CNR as well as getting a promising image quality on detecting diseased cervical lymph node. Moreover, the linear fusion images and80kVp images voltage scan combining SAFIRE technology can improve the lesion display.3.1n comparison with the conventional Ⅲ phase scan, the reduction of radiation effective dose by the second generation DSCT dual energy and phases scan is about25%. Dual energy VNC combining SAFIRE technology can assure image quality and reduce effectively radiation dose on patient.4. The CT value of iodine image has a good correlation with REV value, where we can use CT value to determine REV value, so that we can make a more direct display of the enhancement of the diseased lymph node.5. Nonlinear fusion, iodine and70kev single-energy spectrum image can make a better display of the diseased lymph node.6. If we use each of dual energy scan derived sequence and energy spectrum in combination, which has its significance and value to preoperative assessment on the diseased cervical lymph node.